1. Technical Field
The disclosure relates to a method for forming a semiconductor structure, and more particularly to a method for forming a spacer on a sidewall of an opening in the semiconductor structure.
2. Description of the Related Art
Recently, various three dimensional (3D) memory devices, such as a single gate vertical-channel (SGVC) 3D NAND memory device that has a multi-layer stack structure, have been provided due to the rising demand for superior memory. Such a 3D memory device may possess a higher density memory and excellent electrical characteristics, such as the reliability in data storage and a high operating speed.
In a U turn type SGVC 3D NAND memory device, an inversion gate is used for control assistance. However, during the manufacturing of the inversion gate, over-etching may be occurred, and the structure of the memory device may be damaged. As such, it is relevant to improve the methods for forming the inversion gate in the memory device.